Do you know how much it would cost to have an actual employee, just to show the apartments and answer questions? You're paying them hourly or salary, plus payroll tax, unemployment, all of the other added expenses that a blue state throws on top of that. Plus liability, you now have to comply with every blue state law- oops did you not give the employee their exact mandated lunch time under California's very complex, tough to parse lunch rules? Get ready for a six to seven figure fine. The employee could always invent a discrimination lawsuit, wrongful termination, claim they were injured on the job, etc.
The broker is an independent third party to whom you pay a fixed fee, and have no extra cost or regulatory liability beyond that. A no brainer